30 Meter Telescope Gets Go Ahead...Again

Hawaii’s board of land and natural resources granted a fresh construction permit to the Thirty Meter Telescope (TMT) on 28 September, reviving the fortunes of the US$1.4-billion observatory — at least temporarily.

The permit moves the international project closer towards restarting construction near the summit of the Hawaiian mountain of Mauna Kea. Some Native Hawaiians oppose the TMT, saying that its construction would further violate a sacred mountain that is already home to multiple telescopes.

The board’s decision effectively puts the TMT project back where it was before protestors halted the telescope’s construction in April 2015, just days after it had begun, by blocking the road up Mauna Kea. That December, following months of challenges, Hawaii’s supreme court invalidated the telescope’s first construction permit. The court ruled that the state land board had not followed appropriate procedures because it had approved the first permit, in 2011, before it held a set of public hearings on the case.

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Ground-based photometry of the 21-day Neptune HD 106315c

Ground-based photometry of the 21-day Neptune HD106315c

Authors:
Lendl et al

Abstract:
Space-based transit surveys such as K2 and TESS allow the detection of small transiting planets with orbital periods beyond 10 days. Few of these warm Neptunes are currently known around stars bright enough to allow for detailed follow-up observations dedicated to their atmospheric characterization. The 21-day period and 3.95 R⊕ planet HD106315c has been discovered based on the observation of two of its transits by K2. We have observed HD106315 using the 1.2m Euler telescope equipped with the EulerCam camera on two instances to confirm the transit using broad band photometry and refine the planetary period. Based on two observed transits of HD106315c, we detect its ∼1 mmag transit and obtain a precise measurement of the planetary ephemerids, which are critical for planning further follow-up observations. We have used the attained precision together with the predicted yield from the TESS mission to evaluate the potential for ground-based confirmation of Neptune-sized planets found by TESS. We find that 1-meter-class telescopes on the ground equipped with precise photometers could substantially contribute to the follow-up of 162 TESS candidates orbiting stars with magnitudes of V≤14. Out of these, 74 planets orbit stars with V≤12 and 12 planets orbit V≤10, which makes these candidates high-priority objects for atmospheric characterization with high-end instrumentation.

Sodium Detected in the Atmosphere of hot Jupiter WASP-39b by Ground Based Telescope

VLT FORS2 comparative transmission spectroscopy: Detection of Na in the atmosphere of WASP-39b from the ground

Authors:

Nikolov et al

Abstract:

We present transmission spectroscopy of the warm Saturn-mass exoplanet WASP-39b made with the Very Large Telescope (VLT) FOcal Reducer and Spectrograph (FORS2) across the wavelength range 411-810nm. The transit depth is measured with a typical precision of 240 parts per million (ppm) in wavelength bins of 10nm on a V = 12.1 magnitude star. We detect the sodium absorption feature (3.2-sigma) and find evidence for potassium. The ground-based transmission spectrum is consistent with Hubble Space Telescope (HST) optical spectroscopy, strengthening the interpretation of WASP-39b having a largely clear atmosphere. Our results demonstrate the great potential of the recently upgraded FORS2 spectrograph for optical transmission spectroscopy, obtaining HST-quality light curves from the ground.

Ground-based Transit Observation of the Habitable-zone super-Earth K2-3d

Ground-based Transit Observation of the Habitable-zone super-Earth K2-3d

Authors:

Fukui et al

Abstract:

We report the first ground-based transit observation of K2-3d, a 1.5 R_Earth planet supposedly within the habitable zone around a bright M-dwarf host star, using the Okayama 188-cm telescope and the multi(grz)-band imager MuSCAT. Although the depth of the transit (0.7 mmag) is smaller than the photometric precisions (1.2, 0.9, and 1.2 mmag per 60 s for g, r, and z bands, respectively), we marginally but consistently identify the transit signal in all three bands, by taking advantage of the transit parameters from K2, and by introducing a novel technique that leverages multi-band information to reduce the systematics caused by second-order extinction. We also revisit previously analyzed Spitzer transit observations of K2-3d to investigate the possibility of systematic offsets in transit timing, and find that all the timing data can be explained well by a linear ephemeris. We revise the orbital period of K2-3d to be 44.55612 \pm 0.00021 days, which corrects the predicted transit times in 2019, i.e., the JWST era, by \sim80 minutes. Our observation demonstrates that (1) even ground-based, 2-m class telescopes can play an important role in refining the transit ephemeris of small-sized, long-period planets, and that (2) a multi-band imager is useful to reduce the systematics of atmospheric origin, in particular for bluer bands and for observations conducted at low-altitude observatories.

Will the Okayama Astrophysical Observatory 188-cm telescope Detect Oxygen in Potentially Habitable Exoplanet K2-3d?

A group of researchers from the National Astronomical Observatory of Japan (NAOJ), the University of Tokyo, and the Astrobiology Center among others has observed the transit of a potentially Earth-like extrasolar planet known as K2-3d using the MuSCAT instrument on the Okayama Astrophysical Observatory 188-cm telescope. A transit is a phenomenon in which a planet passes in front of its parent star, blocking a small amount of light from the star, like a shadow of the planet. While transits have previously been observed for thousands of other extrasolar planets, K2-3d is important because there is a possibility that it might harbor extraterrestrial life.

By observing its transit precisely using the next generation of telescopes, such as TMT, scientists expect to be able to search the atmosphere of the planet for molecules related to life, such as oxygen.

With only the previous space telescope observations, however, researchers can't calculate the orbital period of the planet precisely, which makes predicting the exact times of future transits more difficult. This research group has succeeded in measuring the orbital period of the planet with a high precision of about 18 seconds. This greatly improved the forecast accuracy for future transit times. So now researchers will know exactly when to watch for the transits using the next generation of telescopes. This research result is an important step towards the search for extraterrestrial life in the future.

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Robo-AO Kepler Planetary Candidate Survey III: Adaptive Optics Imaging of 1629 Kepler Exoplanet Candidate Host Stars

Robo-AO Kepler Planetary Candidate Survey III: Adaptive Optics Imaging of 1629 Kepler Exoplanet Candidate Host Stars

Authors:

Ziegler et al

Abstract:

The Robo-AO \textit{Kepler} Planetary Candidate Survey is observing every \textit{Kepler} planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. We present in this paper the results of our search for stars nearby 1629 \textit{Kepler} planet candidate hosts. With survey sensitivity to objects as close as ∼0.15" and magnitude differences Δm≤6, we find 223 stars in the vicinity of 206 target KOIs; 209 of these nearby stars have not previously been imaged in high resolution. We measure an overall nearby-star probability for \textit{Kepler} planet candidates of 12.6\%±0.9\% out to a separation of 4.0". Particularly interesting KOI systems are discussed, including 23 stars with detected companions which host rocky, habitable zone candidates, and five new candidate planet-hosting quadruple star systems. We explore the broad correlations between planetary systems and stellar binarity using the combined dataset of \citet{baranec16} and this paper. Our previous 2σ result of a low binary fraction of KOIs hosting close-in giant planets is less apparent in this larger dataset. We also find a significant correlation between binary fraction and KOI number, suggesting possible variation between early and late \textit{Kepler} data releases.

Observing Exoplanetary Atmospheres With Extremely Large Telescopes

Exoplanet Atmospheres and Giant Ground-Based Telescopes

Author:

Crosfield

Abstract:

The study of extrasolar planets has rapidly expanded to encompass the search for new planets, measurements of sizes and masses, models of planetary interiors, planetary demographics and occurrence frequencies, the characterization of planetary orbits and dynamics, and studies of these worlds' complex atmospheres. Our insights into exoplanets dramatically advance whenever improved tools and techniques become available, and surely the largest tools now being planned are the optical/infrared Extremely Large Telescopes (ELTs). Two themes summarize the advantages of atmospheric studies with the ELTs: high angular resolution when operating at the diffraction limit and high spectral resolution enabled by the unprecedented collecting area of these large telescopes. This brief review describes new opportunities afforded by the ELTs to study the composition, structure, dynamics, and evolution of these planets' atmospheres, while specifically focusing on some of the most compelling atmospheric science cases for four qualitatively different planet populations: highly irradiated gas giants, young, hot giant planets, old, cold gas giants, and small planets and Earth analogs.

China has Completed its Giant Radio Telescope

Good ol’ ‘Murica may be ahead of China in development, GDP, and political clout, but China just finished building the world’s largest radio telescope and is now better-equipped at searching for aliens.

According to Xinhua, about 300 “builders, experts, science fiction enthusiasts and reporters” watched the installation of the Five-hundred-meter Aperture Spherical Telescope, or FAST, in the southern Chinese province of Guizhou. The project took five years and $180 million to complete, and the reflector covers the area of roughly 30 football fields.

FAST is almost twice as large as the next biggest radio telescope, which is in Puerto Rico. It will be used for early-stage research by Chinese scientists for a couple years, and then be used more widely. FAST is capable of detecting gravitational waves, pulsars and, eventually, amino acids on other planets.

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Imaging the dust sublimation front of a circumbinary disk

Imaging the dust sublimation front of a circumbinary disk

Authors:

Hillen et al

Abstract:

Aims.

We present the first near-IR milli-arcsecond-scale image of a post-AGB binary that is surrounded by hot circumbinary dust.

Methods.

A very rich interferometric data set in six spectral channels was acquired of IRAS 08544-4431 with the new RAPID camera on the PIONIER beam combiner at the Very Large Telescope Interferometer (VLTI). A broadband image in the H-band was reconstructed by combining the data of all spectral channels using the SPARCO method.

Results.

We spatially separate all the building blocks of the IRAS 08544-4431 system in our milliarcsecond-resolution image. Our dissection reveals a dust sublimation front that is strikingly similar to that expected in early-stage protoplanetary disks, as well as an unexpected flux signal of ~4% from the secondary star. The energy output from this companion indicates the presence of a compact circum-companion accretion disk, which is likely the origin of the fast outflow detected in Hα.

Conclusions.

Our image provides the most detailed view into the heart of a dusty circumstellar disk to date. Our results demonstrate that binary evolution processes and circumstellar disk evolution can be studied in detail in space and over time.

China's New Massive Radio Telescope

Augmenting WFIRST Microlensing Detections with a Ground-based Optical Telescope Network

Augmenting WFIRST Microlensing with a Ground-based Optical Telescope Network

Authors:

Zhu et al

Abstract:

Augmenting the WFIRST microlensing campaigns with intensive observations from a ground-based network of wide-field survey telescopes would have several major advantages. First, it would enable one-dimensional (1-D) microlens parallax measurements over the entire mass range M≳M⊕. For luminous lenses, such 1-D parallax measurements can be promoted to complete solutions (mass, distance, transverse velocity) by high-resolution imaging a few years after the observations. This would provide crucial information not only about the hosts of planets and other lenses, but also enable a much more precise Galactic model. The addition of such a ground-based survey would also yield full 2-D vector parallax measurements, with largest sensitivity to low-mass lenses, which (being non-luminous) are not subject to followup imaging. These 2-D parallax measurements will directly yield mass and distance measurements for most planetary and binary events. It would also yield additional complete solutions for single-lens events, especially those with low-mass lenses. Other benefits of such a survey include improved understanding of binaries (particularly with low mass primaries), and sensitivity to distant ice-giant and gas-giant companions of WFIRST lenses that cannot be detected by WFIRST itself due to its restricted observing windows. Such a ground-based survey can only be conducted in the optical and therefore requires that WFIRST be pointed at lower-extinction fields than is currently envisaged. This would come at some cost to the event rate. Therefore the benefits of improved characterization of lenses must be weighed against these costs.

Exoplanet spectroscopy with diffraction primary objective telescopy

The Giant Magellan Telescope Gets Profiled

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DEdicated MONitor of EXotransits (DEMONEX) Observes Seven Transits of Hot Jupiter XO-4b

The DEdicated MONitor of EXotransits (DEMONEX): Seven Transits of XO-4b

Authors:

Villaneuva et al

Abstract:

The DEdicated MONitor of EXotransits (DEMONEX) was a 20 inch robotic and automated telescope to monitor bright stars hosting transiting exoplanets to discover new planets and improve constraints on the properties of known transiting planetary systems. We present results for the misaligned hot Jupiter XO-4b containing 7 new transits from the DEMONEX telescope, including 3 full and 4 partial transits. We combine these data with archival light curves and archival radial velocity measurements to derive the host star mass M∗=1.293+0.030−0.029M⊙ and radius R∗=1.554+0.042−0.030R⊙ as well as the planet mass MP=1.615+0.10−0.099MJ and radius RP=1.317+0.040−0.029RJ and a refined ephemeris of P=4.1250687±0.0000024 days and T0=2454758.18978±0.00024BJDTDB. We include archival Rossiter-McLaughlin measurements of XO-4 to infer the stellar spin-planetary orbit alignment λ=−40.0+8.8−7.5 degrees.

We test the effects of including various detrend parameters, theoretical and empirical mass-radius relations, and Rossiter-McLaughlin models. We infer that detrending against CCD position and time or airmass can improve data quality, but can have significant effects on the inferred values of many parameters --- most significantly RP/R∗ and the observed central transit times TC. In the case of RP/R∗ we find that the systematic uncertainty due to detrending can be three times that of the quoted statistical uncertainties. The choice of mass-radius relation has little effect on our inferred values of the system parameters. The choice of Rossiter-McLaughlin models can have significant effects of the inferred values of vsinI∗ and the stellar spin-planet orbit angle λ.

Models of the Eta Corvi Debris Disk

Models of the Eta Corvi debris disk from the Keck Interferometer, Spitzer and Herschel

Authors:

Lebreton et al

Abstract:

Debris disks are signposts of analogues to small body populations of the Solar System, often however with much higher masses and dust production rates. The disk associated with the nearby star Eta Corvi is especially striking as it shows strong mid- and far-infrared excesses despite an age of ~1.4 Gyr. We undertake to construct a consistent model of the system able to explain a diverse collection of spatial and spectral data. We analyze Keck Interferometer Nuller measurements and revisit Spitzer and additional spectro-photometric data, as well as resolved Herschel images to determine the dust spatial distribution in the inner exozodi and in the outer belt. We model in detail the two-component disk and the dust properties from the sub-AU scale to the outermost regions by fitting simultaneously all measurements against a large parameter space. The properties of the cold belt are consistent with a collisional cascade in a reservoir of ice-free planetesimals at 133 AU. It shows marginal evidence for asymmetries along the major axis. KIN enables us to establish that the warm dust consists in a ring that peaks between 0.2 and 0.8 AU. To reconcile this location with the ~400 K dust temperature, very high albedo dust must be invoked and a distribution of forsterite grains starting from micron sizes satisfies this criterion while providing an excellent fit to the spectrum. We discuss additional constraints from the LBTI and near-infrared spectra, and we present predictions of what JWST can unveil about this unusual object and whether it can detect unseen planets.

Spin Casting a Segment for the Giant Magellan Telescope

The Capabilities and Performance of the Automated Planet Finder Telescope

The capabilities and performance of the Automated Planet Finder Telescope with the implementation of a dynamic scheduler

Authors:

Burt et al

Abstract:

We report initial performance results emerging from 600 hours of observations with the Automated Planet Finder (APF) telescope and Levy Spectrometer located at UCO/Lick Observatory. We have obtained multiple spectra of 80 G, K and M-type stars, which comprise 4,954 individual Doppler radial velocity (RV) measurements with a median internal uncertainty of 1.35 ms−1. We find a strong, expected correlation between the number of photons accumulated in the 5000-6200$\AA$ iodine region of the spectrum, and the resulting internal uncertainty estimates. Additionally, we find an offset between the population of G and K stars and the M stars within the data set when comparing these parameters. As a consequence of their increased spectral line densities, M-type stars permit the same level of internal uncertainty with 2x fewer photons than G-type and K-type stars. When observing M stars, we show that the APF/Levy has essentially the same speed-on-sky as Keck/HIRES for precision RVs. In the interest of using the APF for long-duration RV surveys, we have designed and implemented a dynamic scheduling algorithm. We discuss the operation of the scheduler, which monitors ambient conditions and combines on-sky information with a database of survey targets to make intelligent, real-time targeting decisions.

30m Telescope Construction Permit Revoked by Hawaii State Supreme Court

Hawaii's supreme court has ruled that the construction permit for the Thirty Meter Telescope (TMT) on top of the mountain Mauna Kea is invalid. The 2 December decision is a major blow to the international consortium backing the US$1.5-billion telescope, and a win for the Native Hawaiians who have protested against its construction on what they regard as a sacred summit.

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Using Micro Lensing to Generate a Galactic Distribution of Exoplanets

Planet Sensitivity from Combined Ground- and Space-based Microlensing Observations

Authors:

Zhu et al

Abstract:

To move one step forward toward a Galactic distribution of planets, we present the first planet sensitivity analysis for microlensing events with simultaneous observations from space and the ground. We present this analysis for two such events, OGLE-2014-BLG-0939 and OGLE-2014-BLG-0124, which both show substantial planet sensitivity even though neither of them reached high magnification. This suggests that an ensemble of low to moderate magnification events can also yield significant planet sensitivity and therefore probability to detect planets. The implications of our results to the ongoing and future space-based microlensing experiments to measure the Galactic distribution of planets are discussed.

Observing F Dwarf ε Aurigae's Protoplanetary Disk for 14 Years

Interferometry of ε Aurigae: Characterization of the asymmetric eclipsing disk

Authors:

Kloppenborg et al

Abstract:

We report on a total of 106 nights of optical interferometric observations of the ϵ Aurigae system taken during the last 14 years by four beam combiners at three different interferometric facilities. This long sequence of data provides an ideal assessment of the system prior to, during, and after the recent 2009-2011 eclipse. We have reconstructed model-independent images from the 10 in-eclipse epochs which show that a disk-like object is indeed responsible for the eclipse. Using new 3D, time-dependent modeling software, we derive the properties of the F-star (diameter, limb darkening), determine previously unknown orbital elements (Ω, i), and access the global structures of the optically thick portion of the eclipsing disk using both geometric models and approximations of astrophysically relevant density distributions. These models may be useful in future hydrodynamical modeling of the system. Lastly, we address several outstanding research questions including mid-eclipse brightening, possible shrinking of the F-type primary, and any warps or sub-features within the disk.